不同土壤水分对信阳五月鲜桃光合作用日变化的影响

Effech of different soil moisture on diurnal changes of photosynthesis in Xinyang May peach

为探讨土壤水分变化对信阳五月鲜桃光合作用日变化的影响,以2年生信阳五月鲜桃幼树为试材,应用Li-6400光合作用测定系统,测定5个水分梯度下信阳五月鲜桃叶片光合参数的日变化过程。结果表明:当土壤相对含水量大于74.9%时,信阳五月鲜桃光合速率、蒸腾速率以及水分利用效率都维持在一个较高的水平。当土壤相对含水量为92.5%时,光合速率和蒸腾速率均有所下降,这主要是由于气孔因素的限制引起的。当土壤相对含水量为55.7%时,光合速率、蒸腾速率和水分利用效率均表现出了较好的变化趋势,但依然低于高水分状态下的光合蒸腾值。当土壤相对含水量低于24.1%时,光合作用降低的主要因素转为非气孔限制因素。信阳五月鲜桃最适的光合作用和最高的水分利用效率的土壤相对含水量为74.9%左右。

hi order to explore the effect of soil moisture on the diurnal wariation of photosynthesis in Xinyang May peach, two-year-old Xinyang May peach saplings were used as test materials, the effect of soil moisture on the diurnal variation of photosynthesis of Xinyang May peach which was determined under five water gradients was discussed by using the Li- 6400 photosynthesis measurement system.The result showed that when the relative soil moisture was more than 74.9%, the photosynthetic rate, transpiration rate and water use efficiency of Xinyang May peach were maintained at a high level. When the relative soil moisture was at 92.5%, the photosynthetic rate and transpiration rate were decreased which was mainly due to the limitation of stomatal factors. When the soil relative moisture was at 55.7%, the photosynthetic rate,transpiration rate and water use efficiency showed a better trend,but it was still lower than the photosynthetic and transpiration value under high moisture state. When the relative soil moisture was lower than 24.1%, the main factor of photosynthesis reduction was non-stomatal limiting factor. The optium photosynthetic and high-efficiency use of water of Xinyang May peach soil moisture was about 74.9%.